The location of a mobile, wireless or wired device is a useful and sometimes necessary part of many services. A Location Information Server (“LIS”) may be responsible for providing location information to such devices with an access network. The LIS may utilize knowledge of the access network and its physical topology to generate and serve location information to devices.
The LIS, in general terms, is a network node originally defined in the National Emergency Number Association (“NENA”) i2 network architecture addressing a solution for providing E-911 service for users of Voice over Internet Protocol (“VoIP”) telephony. In VoIP networks, the LIS is the node that determines the location of the VoIP terminal. Beyond the NENA architecture and VoIP, the LIS is a service provided by an access network provider to supply location information to users of the network by utilizing knowledge of network topology and employing a range of location determination techniques to locate devices attached to the network. The precise methods used to determine location are generally dependent on the type of access network and the information that can be obtained from the device. For example, in a wired network, such as Ethernet or DSL, a wiremap method is commonplace. In wiremap location determination, the location of a device may be determined by finding which cables are used to send packets to the device. This involves tracing data through aggregation points in the network (e.g., Ethernet switches, DSL access nodes) and finding the port for which packets are sent to the device. This information is combined with data available to the LIS (generally extracted from a database) to determine a final location of the device.
In wireless networks, a range of technologies may be applied for location determination, the most basic of which uses the location of the radio transmitter as an approximation. The Internet Engineering Task Force (“IETF”) and other standards forums have defined various architectures and protocols for acquiring location information from an LIS. In such networks, an LIS may be automatically discovered and location information retrieved using network specific protocols. Location information may be retrieved directly or the LIS may generate temporary uniform resource identifiers (“URI”) utilized to provide location indirectly (i.e., location URI). Geodetic and civic positions of a mobile device may be determined as a function of location information from the LIS. There is, however, a need in the art to overcome the limitations of the prior art and provide a novel system and method for a generic application of location determination for network attached devices.
One embodiment of the present subject matter provides a method for determining the location of a target device. The method may comprise receiving a location request for a target device, and determining a plurality of parameters that identify the target device. A most likely path may be selected from a plurality of paths to produce a location of the target device, each path having one or more of the plural determined parameters as an input and one or more measurement results as an output. Measurement information may be collected on the most likely path as a function of one or more of the determined parameters to provide the one or more measurement results. Location information may then be derived for the target device as a function of the one or more measurement results, the derivation utilizing a location determination function that evaluates ones of the plural paths. An estimated location of the target device may then be determined as a function of the respective location information for the selected path.
Another embodiment of the present subject matter provides a method for determining the location of a target device. The method may comprise receiving a location request for a target device and determining a plurality of parameters that identify the target device. Measurement information may be collected as a function of one or more of the plural determined parameters to provide a plurality of measurement results. Location information may then be derived for the target device as a function of one or more of the plural measurement results. This derivation may utilize a location determination function that evaluates one or more paths, each path having one or more of the plural determined parameters as an input and one or more of the plural measurement results as an output. A path from the one or more evaluated paths may be identified as a failed path if location information could not be derived from the identified path. The collection, derivation and identification steps may be iteratively repeated until a most likely path is determined. Upon determining this most likely path, an estimated location of the target device may be determined as a function of the respective location information for the determined path.
A further embodiment of the present subject matter provides an LIS comprising circuitry for receiving a location request for a target device, circuitry for determining a plurality of parameters that identify the target device, and circuitry for selecting a most likely path from a plurality of paths, each path having one or more of the plural determined parameters as an input and one or more measurement results as an output. The LIS may further include circuitry for deriving location information for the target device as a function of one or more measurement results, the derivation utilizing a location determination function that evaluates ones of the plural paths and circuitry for collecting measurement information as a function of one or more of the plural determined parameters to provide the one or more measurement results. The LIS may also include circuitry for determining an estimated location of the target device as a function of the respective location information for the selected path.
These embodiments and many other objects and advantages thereof will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the embodiments.